daniele del re01/16/05 daniele del re (ucsd) 6 aimis to collect as many as possible fully...

Daniele del ReUniversity of California San Diego

01/16/0501/16/05 Daniele del Re (UCSD) Daniele del Re (UCSD) 22

What is the B Beam Physics?What is the B Beam Physics?

ee--DD**

ee++

BBrecoreco

Reconstruct one ofthe two Bs ...

and do it with highefficiency

BBrecoilrecoil

XuXull

The remainder of the eventis the other B

You have a single B beam!!


e-K+

++

(4 )Y S

0

+

0 B

K

BD e[ ]

Fully Recon. Recoil

Event Display Event Display


PEP-II peak luminosity: 9.2 x 1033cm-2s-1

(exceeded design goal 3.0 x 1033)

PEP-II delivered 253 fb-1

BaBar recorded 244 fb-1

PEP-II peak luminosity: 9.2 x 1033cm-2s-1

(exceeded design goal 3.0 x 1033)

PEP-II delivered 253 fb-1

BaBar recorded 244 fb-1

PEP IIPEP II

17fb-1/month


SVT: 97% efficiency, 15 m z hit resolution (inner layers, perp. tracks)SVT+DCH: (pT)/pT = 0.13 % pT + 0.45 % DIRC: K- separation 4.2 @ 3.0 GeV/c 2.5 @ 4.0 GeV/c EMC: E/E = 2.3 % E-1/4 1.9 %

BaBar DetectorBaBar Detector


Aim is to collect as many as possible fully reconstructed B mesons in

order to study the property of the recoil.

Reconstruct B D(*) n mK pKs q 0 but the intermediate resonances

are not requested. This is the so-called SemiExclusive Reconstruction.Two steps:

Reconstruction of the D meson in hadrons

Reconstruction of the B meson in hadrons

the signal box is defined using two variables:

Iterative method.

Finally ~1100 modes ordered by purity.

In events with multiple candidates, the best one is selected by:Looking at the best E within the same mode

Looking at the best purity if different modes

Fully Hadronic TagsFully Hadronic Tags

Resolution from beam energy

Sensitive to E measurement

Breco Breco TagsTags


How Many B MesonsHow Many B Mesons

The final efficiency is ~0.4% (per bbbar pair)~4000 B/fb-1

1500 B0/fb-1

2500 B+/fb-1

purity

Yield

Purity can be optimizeddepending onthe analysis cutson the recoil

Full sampleFull sample(~30% purity)


Low purity could be an issue depending on the analysis. Purity improves a lot once cuts on the recoil are applied. For instance continuum is removed by the presence of a high energy lepton.

Lepton request (p*>1.0GeV)

S/B~0.3

S/B~2.5

Effect of Cuts on the RecoilEffect of Cuts on the Recoil

Continuum:before and after request leptonwith p*>1.0GeV


Semileptonic TagsSemileptonic Tags

ee--

ee++

BBsemilsemil..

BBrecoilrecoil

llXX

DD00XX

llB- D0 l- X K- +

K- + 0

K- + - +

K0s

+ -

X0 system: or 0 only candidates from possible D(*)0 D0 / 0 transitions

A different kind of tags can be obtained by using charm semileptonic B decays B D l- X, considering just the D meson and the lepton.Additional cuts are applied to remove background (for instance cosine of theangle between B and Dl system)

Pro:Higher stat.

Cons:One missing neutrino(compared with hadronic tags)

SemilSemil TagsTags


l+

D0

Partially Reco TagsPartially Reco Tags

B D* l X decays are partially reconstructed

Using the soft from the D* D0 soft

Selected by the following variables:

Some preselection cuts on shape and multiplicity

lepton mom. (p*>1.3GeV)

soft pion mom. (50MeV<p <200MeV)

lepton- Vtx probability

Signal yield is extracted via M 2 (mis. mass squared).

D* is assumed to be collinear with the soft

Then:

Rig

ht s

ign

Rig

ht s

ign

Wro

ng s

ign

Wro

ng s

ign

*

0 *

* 2 2

( )s DD lB D

E ME M p p p

M

Partial TagsPartial Tags

Cons:

Missing and mesons that can contaminate recoil side

Pro:

Even higher stat.


h+

h-

Untaggedl+

D0

Partial Recol+

D0

Semileptonic Reco

l-Y(4S)Y(4S)

Reco edMissed (or not reconstructed)

Summary on Experimental TechniquesSummary on Experimental Techniques

Method tag side

(nh ,m )

soft l (D0 X)

D(*) l ( X)

D(*) X

efficiency purity

+

D0

Fully Had. Reco


SemilSemil TagsTags

UntaggedUntagged


No recoil

Recoil of partiallyreconstructed D*l

Recoil of B D(*)lnX

Recoil of fully recon. B D(*)X


Recoil in Semileptonic DecaysRecoil in Semileptonic Decays

Only one missing neutrino in the event.

system is overconstrained, we can

use kinematic fits

Typical cuts:One and only one lepton with p*> 1 GeV/c Correlation between lepton charge and Breco flavor Cut on the missing mass: Mmiss

2 < 0.5GeV2

charge conservation: Qtot=0Partially reconstructed neutrino to reject

B0 D* l events

It is possible to reconstruct directly X mass in

B Xl resolution in m(X) ~ 300MeV

+

D0

l-Y(4S)Y(4S)

Possible measurements:Possible measurements:

inclusive B Xl (Vcb)

inclusive B Xul (Vub)

exclusive B ( l (Vub)

exclusive B D(*,**)l

exclusive B D(*)

Published or preliminaryFuture

SemileptonicSemileptonicdecaydecayB Xl


Incl. Semileptonic: HQE Expansions Incl. Semileptonic: HQE Expansions

Heavy Quark Expansions, tool to correct for QCD effectsExpansion in terms of 1/mb and s(mb)Separate short- and long-distance effects at ~ 1 GeV

Perturbative corrections calculable from mb mc s(mb)Non-perturbative parameters cannot be calculated

We choose calculation by Gambino & Uraltsev hep-ph/0401063 & 0403166

Kinetic mass scheme to E moments mX moments

8 parameters to be fitted

We measure moments of the mass of the X system as a function of minimum lepton energy El

cbV bm cm 2 2G

3D

3LS

( )cB XB l

kinetic

chromomagnetic

Darwin

spin-orbit

2(1/ )bmO

3(1/ )bmO

2( )sO

( )sO

3(1/ )bmO


2/350)( cMeVM x

high mass charm states

Mx2[GeV2/c4]

To eliminate dependence of moments on uncertain BF and unknown masses of high mass charm mesons we calibrate mx measurement

Calibrate mx based on MC simulation

Linear relation between mxmeas and mX

true

Validate calibration with excl. B D(*)

Moments corrected for detector effects and bkg

Hadron mass moments

7114 Events

D, D*

mxm

eas

(Gev

)

mXtrue (GeV)

Even

ts/0

.5 G

eV2

mX2 (GeV2)

Mass Moments in B Xl (Vcb)Mass Moments in B Xl (Vcb)



MX moments

E moments

= used, = unusedin the nominal fit

Red line: HQE fitYellow band: theory errors

BABAR

2/ndf = 20/15

M1x M2

x M3x M4

x

M0l M1

l M2l M3

l

HQE Fits (Vcb)HQE Fits (Vcb)


HQE Fit Results (kinetic mass scheme)HQE Fit Results (kinetic mass scheme)

s

s

s

3exp HQE th

exp HQE

exp HQE

exp HQE

2 2exp HQE

2exp HQE

(41.4 0.4 0.4 0.6 ) 10

(10.61 0.16 0.06 )%

(4.61 0.05 0.04 0.02 )GeV

(1.18 0.07 0.06 0.02 )GeV

(0.45 0.04 0.04 0.01 )GeV

(0.27 0.06 0.03 0.0

cb

c

b

c

G

V

m

m

B l

s

s

s

2

3 3exp HQE

3 3exp HQE

2 )GeV

(0.20 0.02 0.02 0.00 )GeV

( 0.09 0.04 0.07 0.01 )GeV

D

LS

Separate fits to hadron and lepton moments give consistent results

Considerable improvement in precision for |Vcb| (±2%) and Bcln (1.6%)

and quark masses (factor of 6), as well as HQE parameters

BABAR

Breco Breco TagsTags80fb-1


Our default

Alternative

OPE

CLEO

BELLE

Incl. Vub: Theory and UncertaintiesIncl. Vub: Theory and Uncertainties

Relevant issueshadronization effects and Fermi motion (b quark mass) non-perturbative parametrizations (Shape Function, SF) affected by large uncertainties.

Two approaches to extract |Vub| and estimate theo. systematics:1. DeFazio-Neubert paper (DFN ), tri-differential

parametrization (Ee,mX,q2) to extrapolate. |Vub| extracted by

2. q2 vs mX approach by Bauer et al. (BLL ). partial BR with q2 vs mX cut. |Vub| is extracted using

Dependence on SF (here in G) is much reduced.

Theo. uncertainties on non-perturbative effects are evaluated using SF and SF ellipse from b s from CLEO. Belle ellipse as an alternative.

( ) 1.610.00424 (1 0.028 0.039 )

0.002 b

uub OPE m

B

B B X l psV

2 2 423

2 5

1.7 / , 8 /( ; )192Xu

ubB F b

m GeV c q GeV cB B X lV

G m G

l

ubVub


Incl. Vub : mX vs. q2Incl. Vub : mX vs. q2


3(4.92 0.39 0.36 0.46 ) 10ub stat exp syst theo systV

80fb-1

Unfolded mX spectrum and cumulative distribution for b ul decaysStability of |Vub| as a function of the q2 cut

3( ) (0.88 0.14 0.13 0.02 ) 10bu stat exp syst (m ,a) systB B X l

210.545 / ; 0.342

SF SFGeV c2

10.435 / ; 0.16SF SFGeV c

210.800 / ; 1.22

SF SFGeV c

(using BLL)

BLL=Bauer et al.DFN=De Fazio,Neubert


Vub Summary Vub Summary

We measured |Vub| with different experimental inclusive techniques:

Dominant error from modellization of non-perturbative effects (Shape Function, SF).

We measured the unfolded mX distribution. In future b ul decays can be used to put constraints on SF parameters. FUTURE: use b ul m(X) moments to extract Vub and non-perturbative params.

SF param. fromCLEO b s

SF param. fromBELLE b s


Excl. Vub: Theory and UncertaintiesExcl. Vub: Theory and Uncertainties

primary challenge is calculation of the form factors (containing hadronization effects and non-pert. contributions) large uncertainties both extrapolation to full phase space and determination of |Vub| different theoretical models predict different q2 distributions.discriminate among models by a precise measurement of differential BRs.

The differential branching ratio can be related to |Vub| by the following relation

The bigger the integrated region the smaller the uncertainty on |Vub|

Recoil approach reduces the extrapolation errorssince we can use looser cuts! (less background)

0

2 3022 2 2

2 3

( )sin ( )

(cos ) 32F

ub WlBWl

G kdB B lV f q

dq d

B l


Exclusive VubExclusive Vub

Partial Tags: measurement in bins of q2(0-8-16GeV2/c4)

Signal yields are extracted by fitting M 2 ( mass squared):

Breco Tags: 9 B Xul modes: Xu= a a

Approach similar to the inclusive analysis but resonances are exclusively andfully reconstructed on recoil.



0B l0B l0B l

0 4( ) (2.57 0.52 0.59 ) 10stat systB B l

0 4( ) (1.08 0.28 0.16 ) 10stat systB B l

0 4( ) (1.46 0.27 0.28 ) 10stat systB B l

80fb-1

(upper limits for a a , results

in backup slides)

q2 < 8GeV2/c4

Partial TagsPartial Tags Breco Breco TagsTags Breco Breco TagsTags


Recoil in Leptonic Decays (and h )Recoil in Leptonic Decays (and h )

Recoil is useful in the leptonic decays with many neutrinos but we cannot use kinematic constraints anymore

Typical cuts:

require the recoil to have

exact charged-particle content expected

for signal

number and total energy Eextra of neutrals observed

less than an analysis-dependent threshold

tagging efficiencies can be checked by

double-tagging

apply anti-continuum shape cuts

+

D0

Y(4S)Y(4S)

Measurements:Measurements:

B

B

B K

B


l

LeptonicLeptonicdecaydecayB


Leptonic B decays to + , Leptonic B decays to + ,

Leptonic decays of heavy-quark mesons provide a laboratoryFor testing straightfoward SM predictions:

For searching for non-SM effects in highly suppressed processes. Some new-physics in loops (e.g., SUSY) can enhance these by orders of magnitude.

b

u

l+W+

B+

2

2

222

22

18

)(B

llBBB

ubF

m

mmmf

VGlB

Calculable in Lattice QCDIn SM: B(B+ + ) ~ (9.3±3.9)×10-5 (PDG 04 Vub, fB)

(pred.) B(B+ + ) ~ (4.2±1.8)×10-7

Note helicitysuppression

b

d

l+,W+

Wl ,l ,

B0b

d

l+,

qu

W l ,l ,

b

d

l+,W

l ,l ,

,Zqu

qu

,ZIn SM: B(B0 + ) ~ 8×10-11

(pred.) B(B0 ) ~ zero( via Z only)


B+ + analysis IB+ + analysis I

Semileptonic tags: ML fit to EextraConsider e e and Signal: 14.8 ± 6.3 eventsBackground: 115.2 ± 11.8 eventsSignificance as a signal: 2.3 (stat. only)Limit (CLs method, incl. syst.):

B(B+ + ) < 6.7×10-4 (90%CL)

Hadronic tags: event counts+ , + 0 , + + , e e ,

Signal in kin./Eextra regions: 15 events

Background: 17.2 ± 2.1(stat) ± 1.3 (syst) events

Limit (L-ratio w/ null hypothesis):B(B+ + ) < 4.2×10-4 (90%CL)

Combined limit: B(B+ + ) < 4.2×10-4 (90%CL)

branchingfraction

eff c ygiven tag

backgr ndestimate Nobs

BaBarpreliminary

BB pairs used: (88.9±1.0)×106


SemilSemil TagsTags


B+ + analysis II D*l tagsB+ + analysis II D*l tags

Refinement of semileptonic part of analysis I

Tighten tag selection to require clean D*

Consider + , + 0 , + + , e e , and

Mode-dependent kinematic selections

Determine signals by counting events in Eextra regions

+ ++ 0+e eMode

25.1 ±3.429.8 ±5.155.3 ±7.48.1±2.115.2±3.1BG incl.

systematics

2630721013Observed

Result:B(B+ + ) < 4.3×10-4 (90%CL)

Combined with hadronic tags:(independent, 88.9M BB)

B(B+ + ) < 3.3×10-4 (90%CL)

(Signal MC scaled to BF=10-3)

Also recall (PRL 92, 221803, 04)BaBar B(B+ + ) < 6.6×10-6

ValidationsSignal efficiency, Eextra:

Double tagsBackgrounds:

Control samples with extra tracks

Using (124.1±1.4)×106

BB pairs

SemilSemil TagsTags


B0 invisible ( ) analysisB0 invisible ( ) analysis

Semileptonic tags only: B0 D(*)+l (D*+ D0 +)

Require nothing in recoil: no charged tracks, limited neutrals

Signal obtained from ML fit to Eextra (KEYS shapes from MC):

: Signal: 17 ± 9, background 19 + 10 events

: Signal: 1.1 + 2.4 , background 28 + 6

Upper limits:Systematics for ( ):

Additive: 7.4 ( 4.3 ) events

Multiplicative: 10.9% ( 11.1% )

Frequentist limit-setting procedureSystematics taken as Gaussian

B(B0 invisible) < 22 × 10-5 (90%CL)B(B0 ) < 4.7 × 10-5 (90%CL)*

8

1.9 5

*Depends on constituent quark model for Dalitz plot shape(Lu & Zhang, Phys. Lett. B 381, 349 (1996))

BB pairs used: (88.5±1.0)×106

SemilSemil TagsTags


l

B decays to K/ +B decays to K/ +

MotivationThe flavor-changing neutral current decays B K/ + occur in the Standard Model via one-loop radiative penguin and box diagrams:

SM expectation: B(B+ K+ ) ~ (3.8 + 1.2) × 10-6, B(B+ + × 10-7

Their analysis is theoretically very clean; observation of these processes would be complementary to the observation of B K(*) l+l and will help in understanding the basic Standard Model physics of such diagrams.

These also present another opportunity for the observation of new-physics effects in the loops.

0.6


B+ K/ + analysisB+ K/ + analysis

Uses tags of both typesSignal obtained from Eextra/pK region

Combined limit:B(B+ K+ ) < 5.2×10-5 (90%CL)

Also possible to set limit on B+ +

Change PID requirement; use only hadronic analysis: B(B+ + ) < 1.0 ×10-4 (90%CL)

hadronic semileptonic

Points: data; solid: background MC; dashed: signal MC (arbitrary scale)

Eextra

pK

BB pairs used: (88.9±1.0)×106

BaBarpreliminary

BaBarpreliminary

BaBarpreliminary

BaBarpreliminary

6.2×10-5

0.055±0.005

3

3.9±1.1

Hadronic

0.115±0.009Efficiency (%)

7.0×10-5Limit (90%CL) onB(B+ K+ )

6Signal events

3.4±1.2 (non-peaking)

Background events (incl. systematics)

SemileptonicTags

SemilSemil TagsTagsBreco Breco TagsTags


Summary of Leptonic Decays (and h )Summary of Leptonic Decays (and h )

Upper limits on branching fractions of several rare leptonic and/or FCNC decays of B mesons useful as

checks of basic predictions for weak decays of heavy-quark mesons (e.g., fB), and

probes for new physics beyond the Standard Model

These decays have not yet come into sight

but some are now within an order of magnitude or less of the SM expectations

Some of these will very likely be observed in few years from now

10- 11 10- 10 10- 9 10- 8 10- 7 10- 6 10- 5 10- 4 10- 3

(absent in SM)

+K+

+


Recoil in Hadronic DecaysRecoil in Hadronic Decays

In principle no neutrinos in the event. Full event reconstruction could be done but

too low efficiencies. Inclusive approach used instead.

Typical approach:

reconstruct exclusively a meson charmed (D0/±(*) or Ds

(*) )

charged pion or kaon

Measure the inclusive BR (i.e. BR(B DX)) by normalizing to the total number of fully reconstructed tags

. or ..

Study inclusively the missing mass of the event (measuring BRs, checking for new resonances)

+

D0

D0

Y(4S)Y(4S)

Measurements:Measurements:

B D0/±X, B DsX

B D0/±(*,**)

B D0/±(*)X B Ds(*)X:

study of missing mass


+

0

HadronicHadronicdecaydecayB DX


cc c

XN ( B X X )

Inclusive charmInclusive charm

We define:Flavor correlated charmcorrelated charmproduction from dominant b c transition

Flavor antianti--correlated charmcorrelated charmproduction from W- cs decay

Hadronization models (Heavy Quark Expansion)predict average charm multiplicity in B decays, nc 1.2-1.3

b cu u

W -

B-

sc

[charge-conjugationimplied everywhere]

)(,,,, ,0 ccDDDX ccc S

) ( Nc

c XXB cX

cc cNn N

[Bagan et al. PLB351(1995)Buchalla and Dunietz, PLB364(1995)Neubert and Sachrajda, Nucl.Phys.B483(1997)]

0, , , , ( )Sc cX D D D cc


Inclusive CharmInclusive Charm

Data sample: 89 million B pairs

D0

D+

D+S

D0

D+

D-S

-c

B- B-

+c

Signal41 9

Signal33 9

Signal11 5

Signal82 11

Signal262 29

Signal98 20

Signal1273 42

Signal160 16

Linear bkg:combinatorics

Blue-shaded areas: true charm particlesfrom background of misreconstructed B

Significant production ofcorrelated D0 and D+

Ds correlated production small. Anti-correlated dominant.



Inclusive Charm: ResultsInclusive Charm: Results

(B XcX) %(B XcX) %Xc

2.0 ± 1.2 ± 0.2+0.7-0.4

<3.9 at 90%CL

4.9 ± 1.7 ± 0.4+1.8-1.0

+c

10.9 ± 2.1 ± 0.8+3.8-2.33.9 ± 1.7 ± 0.4+1.3

-0.8

< 8.7 at 90% CLD+

s

2.3 ± 1.8 ± 0.3+0.2-0.2

< 5.1 at 90% CL

39.7 ± 3.0 ± 2.8+2.8-2.5D+

6.3 ± 1.9 ± 0.5+0.2-0.251.1 ± 3.1 ± 2.5+1.3

-1.3D0

anti-correlatedcorrelated

(B XcX) %(B XcX) %Xc

2.9 ± 0.8 ± 0.3+1.1-0.63.5 ± 0.8 ± 0.3+1.3

-0.8+

c

14.3 ± 1.6 ± 1.5+4.9-3.00.5 ± 0.6 ± 0.2+0.2

-0.1

<2.2 at 90% CLD+

s

3.8 ± 0.9 ± 0.4+0.3-0.39.8 ± 1.2 ± 1.2+0.8

-0.7D+

9.8 ± 0.9 ± 0.5+0.3-0.379.3 ± 2.5 ± 4.0+2.0

-1.9D0

anti-correlatedcorrelated

No evidence of B c+

c K

First measurement of D+s correlated

Sizeable c production

062.00.0371.313n

020.00.0220.330N

046.00.0300.983N

063.0042.0c

051.0031.0c

028.0023.0c

058.00.0621.276n

012.00.0360.237N

049.00.0511.039N

066.0046.0

0c

039.0024.0

0c

039.0031.0

0c

using

(B c X) = (B c X) - (B c+

c K) (B c X)

neglecting (B c X)

using (B (cc) X) = (2.3 ± 0.3) %

We get

BB--

BB00


BB

b

d

W+

W

B0

b

d

qu

W

b

d

W

,Zqu

qu

,Z

SM prediction: B(B0 + ) ~ 3×10-8

butPotential enhancements up to 102

due to new physicsNo published experimental UL

Very difficult measurement

~2/3 of the B0 + - events contain at least one KL

Many neutrinos, large missing mass

This measurement is possible only on the recoil


B DB D

D0 K 4%K 0 13%K 7%K 0 4%KS

0 1%KS 2%KS

0 4%Total 35%

11%25%

Total 36%

signal MC( )

BG

Decay modes:

Channel sensitive to new Physics

Presence of large missing mass tags these events

Lots of advantages in studying this channel on the recoil (nice miss. mass resolution, no B0-B+ crossfeed, direct reconstruction of thehadronic mass)

( )

( )

BR B DBR B D


An interesting application

is in measuring b s branching

ratio and photon spectrum.

It presents many advantages

with respect to the fully inclusive

approach:1) Continuum is subtracted by fitting mes in the reconstructed side

2) Exact boost in the recoiling B meson rest frame no smearing due to the B meson momentum in the Y(4S) frame

3) Perfect tagging. You can distinguish between B0-B0bar and B+-B-

4) You could in principle separate and measure d contribution

Assuming an efficiency of 50% in the recoil:

Nevents/fb-1 = 3·10-4 * 4·103/fb-1 * 0.5 = 0.6/fb-1

Perspectives on B XsPerspectives on B Xs

MCMC

600ev. in 1 600ev. in 1 · abab--11

B.R.B.R. NBrecoNBreco.. EffEff....

~250 ~250 fbfb--11



Study of X mass recoiling to a /KStudy of X mass recoiling to a /K

Pick up a track on the recoil

Reconstruct the missing mass as difference from the Y(4s)

(P(X)=P(Y(4S)-P(Breco)-P( ))

Extract BRs for B D,D*,D**

Advantages

Clean way to study and measure the

decays to excited states (B D**

Small systematics (no intermediate BRs)

Possibility to study ratio of BRs with

negligible systematic uncertainties

D D* D**



Study of X mass recoiling to a D+/0(*)Study of X mass recoiling to a D+/0(*)

Exclusively reconstruct charmed meson

Reconstruct the missing mass as difference from the Y(4s)

(P(X)=P(Y(4S))-P(Breco)-P(D))

Apply kinematic fit to improve the

resolution of Mx

Extract BRs for B D±,0(*)Ds,Ds*,DsJ

Advantages

Small systematics (no intermediate BRs)

B D±,0(*) DsJ with no assumption on DsJ BRs

Possibility to study ratio of BRs with

negligible systematic uncertainties

Check for possible new resonances


Ds

D*s

DsJ


Time dependent CP analyses? Lots of advantages:1. Very nice vertexing (usual is 70 m 180 m 70 m 70 m)

2. Almost perfect tagging

3. B0-B+ separation

4. You can have an inclusive reconstruction on the recoil side

Possible examples:

B0 XS ????

Direct CP:

Possible example: B+ D0K+ ????

CP analyses?CP analyses?

brecobreco taggingtagging brecobreco brecobreco

reconstructed inclusively to enlarge stat.


10

100

1,000

10,000

100,000

00 02 04 06 08 10 12 14

Year

-1

today SuperBFactory

Conservatively 1ab-1

Belle+BaBar 2007

Which luminosity in the next years?Which luminosity in the next years?


Possible upgrade of BaBar detector:

Emphasis on high segmentation, fast integration time, radiation hardness

DIRC

IFR upgraded(ongoing)

New EMC liquid Xe

New tracker- Two inner pixellayers

- Seven(?) thindouble-sidedSi-strip arch layers

New DIRC(s) with compact readout

SuperB Detector ProposalSuperB Detector Proposal


Summary on SensitivitySummary on Sensitivity

Xcl XulsD

l

l

*These numbers do not consider S/B (just N events for a reasonable set of cuts)**Some of them use more than one type of tags. If not, they could be improved

SuperBSuperB


ConclusionsConclusionsRecoil approach provides the best environment to perform

analyses in different fields:Semileptonic Decays: inclusive and exclusive Vub/Vcb, D ,

Leptonic Decays: ,

Hadronic Decays: inclusive charm production, study of missing mass in B DX decays

BaBar published already many new results using this method

(6 publications and lots of preliminary results).

~all statistically limited

This method will be crucial in future when larger statistics

will be collected by BaBar and in particular if a

SuperBFactory will be built.


Incl. Vub: mX vs. q2Incl. Vub: mX vs. q2

Extension of the already published result (PRL92,071802).

Recoil selection and reconstruction of X system:One and only one lepton with p*> 1 GeV/c Correlation between lepton charge and Breco flavor Cut on the missing mass: Mmiss

2 < 0.5GeV2, charge conservation: Qtot=0Partially reconstructed neutrino to reject B0 D* l eventskinematic fit (2-C): improve hadronic mass resolution Kaon veto

Systematics due to lepton ID and tag normalization reduced by measuring

a ratio of BRs

mX <1.7GeV and q2>8GeV2 using the approach by Bauer et al. Dependence on

shape function parameters is much reduced

This approach and sample have been also used to unfold the mX spectrum.


/

( )

( )u

u sl

B B X lR

B B Xl


Inclusive: mX and mX vs. q2Inclusive: mX and mX vs. q2



Inclusive: Unfold Had. Mass SpectrumInclusive: Unfold Had. Mass Spectrum

mX spectrum can be converted in a universal

variable by unfolding detector and selection effects.

relationship between measured and true spectra is:

where is the detector response

matrix, in general is non-invertible.

Unfolding method is based on procedure

specified in hep-ph/9509307.

Systematics effects are properly taken into account.

First and second moment of the b ul mX

distribution are extacted:


µmeas truex A x

r r µA

80fb-1


Exclusive: B ( a0) lExclusive: B ( a0) l

9 B Xul modes are studied:

Xu= a a

Resonances are exclusively reconstructed on the recoil.

Similar cuts as for the inclusive mX analysis, such

as p*>1GeV and miss. mass squared of the event.

Further per mode cuts to reject b c and

crossfeed background are used

(~all)50- 100985a00l

(~all)50- 100985a0 l

-957.8´l

-547.8l

8.5782.6l

150775l

150775l

-134.98l

--139.57l

Decay modesWidth(MeV)Mass(MeV)


80fb-1


Exclusive: B ( a0) lExclusive: B ( a0) l

Similar approach to the inclusive analysis but

resonances are exclusively and fully reconstructed on recoil.

We measure:

0 4( ) (2.57 0.52 0.59 ) 10stat systB B l

0 4( ) (1.08 0.28 0.16 ) 10stat systB B l 0 0

0 0

0

( ) 2 ( )

( ) 2 ( )

( ) ( )

B B l B B l

B B l B B l

B B l B B l

These two results make use of:

4( ) 1.2 10 (90% )B B l CL4( ' ) 4.5 10 (90% )B B l CL

0 0 0 40 0( ) ( ) 5.3 10 (90% )B B a l B a CL

40 0( ) ( ) 3.3 10 (90% )B B a l B a CL


80fb-1

Systematics are dominated by MC statistics.Large systematics due to non-resonant contribution in B l . Theoretical systematics are small (~ 4-7%)

0B l

0B l0B l


Results (80fb-1)Results (80fb-1)

B± l

B± l

B0 l

B0 l

0 4( ) (0.89 0.34 0.12 ) 10stat systB B l

0 4( ) (0.91 0.28 0.14 ) 10stat systB B l

0 4( ) (3.5 1.1 0.7 ) 10stat systB B l

0 4( " " ) (1.04 0.39 0.16 ) 10stat systB B l

4( ) (1.26 0.55 0.24 ) 10stat systB B l


Results (80fb-1)Results (80fb-1)

B± l B± l 4

4

( ) (0.39 0.41 0.22 ) 10

( ) 1.2 10 (90% )

stat systB B l

B B l CL

4

4

( ' ) (2.7 1.2 0.5 ) 10

( ' ) 4.5 10 (90% )

stat systB B l

B B l CL

0 0 00 0

4

0 40

( ) ( )

(2.7 1.4 0.9 ) 10

( ) 5.3 10 (90% )

stat syst

B B a l B a

B B a l CL

0 0

4

40

( ) ( )

(0.7 1.6 0.3 ) 10

( ) 3.3 10 (90% )

stat syst

B B a l B a

B B a l CL

B± a l B0 a l


0 4( ( ) (1.22 0.26) 10 )B B l

Vub measurements with BaBarVub measurements with BaBarVub(x10-3)Pros&ConsS/Bmethod

Very small bkg~no cut on kinemSmall statistics

1 20

Total rate using Form Factors calc.

Low backgroundVery small syst. on SF param.Small statistics

~2mX vs q2 analysis mX<1.7 GeV/c2 and q2 >8.0 GeV2/c4

Vub using Bauer et al.

Low backgroundHigh resolutionLow statisticsShape func. syst.

~1.7mX analysis (1-D)mX<1.55 GeV/c2

Total rate using DeFazio-Neubert

High statisticsLower syst. on shape functionsBkg subtraction

~0.5Ee vs q2 and neutrino reconstructionEe>2.0GeV and sh<3.5 GeV2/c4

Total rate using DeFazio-Neubert

High statisticsDuality valid for tight Ee cuts?Bkg subtraction

0.05 0.2Electron spectrum endpointEe>2.0GeVTotal rate using fu from CLEO

UntaggedUntagged

UntaggedUntagged





inclusive

inclusive

inclusive

inclusive

exclusive

0.620.364.63 0.47exp theo

3.94 0.23 0.42exp theo

0.690.454.77 0.40exp theo

4.92 0.53 0.46exp theo


Vub measurementsVub measurements


Conclusions for Exclusive DecaysConclusions for Exclusive Decays

We also developed novel methods to measure EXCL. CHARMLESS decays:

Breco tags:

Semil tags:

AVERAGE

0 4( ) (2.57 0.52 0.59 ) 10stat systB B l

0 4( ) (1.08 0.28 0.16 ) 10stat systB B l

0 4( ) (1.46 0.27 0.28 ) 10stat systB B l

0 4( ) (1.22 0.19 0.18 ) 10stat systB B l


B0 invisible (+ gamma) is unmeasured, sensitive to new physicsSeveral new physics models predict a small but significantly nonzero branching fraction for B0 invisible

Dedes, Dreiner, & Richardson hep-ph/0106199(SUSY model, attempt to explain NuTeV anomaly, (B0 invisible) = O(10-6)) Agashe, Deshpande, & Wu hep-ph/0006122Agashe & Wu hep-ph/0010117Davoudiasl, Langacker, & Perelstien hep-ph/0201128(Large extra dimensions, (B0 invisible) = O(10-7))

Diagrams (in SM):

Can be measured via reconstruction of tag-side B + nothing else this analysis uses semileptonic tags.

Recoil Workshop 10/1/2003 invisiinvisiBB00lele J. Albert 3

B : MotivationsB : Motivations


1.81.023.510.3Current (A)

x=450/y=10x=15/y=1.5*(mm)

40/2.5x= 44/y=0.44Emittance(nm)

20057lifetime (min)

x= 147/y=5x= 81/y=0.8Beam spot ( m)

0.070.10Tune shift

8007000#bunches

3.19.03.58.0E(GeV)

e+e-e-e+Beam

Super B-Factory B-Factory

Beams in a SuperBBeams in a SuperB


Super B Factory EnvironmentSuper B Factory Environment

Reaching 1036 implies that a series of issues have to be faced:

Higher beam currents, stronger focusing, continuous injection

Increased background and higher rates for detector

Radiation damage

High occupancy

SVT Dose

SVT Hardness

7 Mrad/yr DCH Occupancy >100% Occupancy

NEED NEW DETECTOR


Detector IssuesDetector Issues

Super BaBar detector designed to have sufficient granularity todeal with the high occupancyHowever, some issues need investigating

tracking efficiency and fake trackscalorimeter resolution, fake photons, ability to veto pi0, etcparticle ID performanceetc

! studies yet to be performed

Some detector R&D is needed for:

thin (100 m) Si detector and low-power electronics

small-cell drift chamber in high radiation environment

focusing DIRC with pixel PMT

choice of EM calorimeter: liquid Xe vs. (fast) crystals

technology for muon ID


BaBar+ Belle (2007)

SuperBaBar (/year)

SuperBelle (2010)

LHCb (/year)

BTeV (/year)

Lumi Nbb

1ab-1

2x109 10ab-1

2x1010 3ab-1

6x109 1012 1011

sin2

efftag

0.07 900

0.025 9000

0.04 3000 1000 1500

Ceff

460 0.15 9o

4600 0.05 3o

1500 0.09 5o

- -

sin2

0.06 0.03 0.06 0.06

Bs - - - 5o 5o

(Bd DK) 7o 5o 6o 7-8o 13o

(Bs DsK) - - - 14o 8o

sin2 KS) 0.2 0.07 0.1 0.2 0.12

N(Xsll) 700 7k 3K 4K K*ll

4K K*ll

sin2

(J/ J ) - - - 0.06 0.02

Rough physics reachesRough physics reaches

Approximate numbers that were used to stir the discussion

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